More than half of patients with breakthrough disease and adequate follow-up (26/52 patients) who were switched to twice-weekly treatment had no further clinical relapses, new T2 lesions, or enhanced lesions on MRI, or worsening of Expanded Disability Status Scale (EDSS) during at least 14 months (range 14 to 192 months) of follow-up, according to Robert Baumhefner, MD, of the VA Greater Los Angeles Healthcare System.